Administration of the long-acting beta 2-adrenoceptor agonist salmeterol from a new, easy-to-operate, multidose powder inhaler (Diskus) containing 60 sealed doses in a foil strip has been compared with administration from a Diskhaler inhaler in a multicenter, double-blind, double-dummy, parallel-group study. Asthmatic patients taking anti-inflammatory treatment, with baseline FEV1 > or = 60% and < or = 90% predicted were treated for 4 weeks with salmeterol 50 micrograms twice daily from either the Diskus or Diskhaler inhaler. The two treatments were equivalent (90% CLs for the difference in mean morning PEFR: -2.2, 8.7 L/min). The Diskus inhaler was rated easier to use and was preferred by more patients than the Diskhaler inhaler (73% vs. 15%).